XVI International Botanical Congess

Such processes around of the developing microspore as (1) deposition of callose, (2) formation of a glycocalyx matrix, (3) synthesis of sporopollenin precursors, their spatial organization, (4) realization of the diversity of archtectonic design of exines, (5) relationships with tapetum are still far from being clear. Our ultrastructural ontogenetic studies allow to suggest (1) unexpected role of callose which forms a narrow space near the plasmalemma, (2) colloid state of the glycocalyx inside this narrow space, (3) self-distribution of matrix molecules, and precise localization of enzyme molecules for sporopollenin by self-assembly, (4) slight variations in taxon-specific enzyme structure result in different orientation of enzyme molecules through primexine matrix and lead to diverse exine patterns, (5) tapetum shows unusual intermediate types.